1. Field of the Invention
The present invention relates to an ophthalmologic apparatus, which acquires information specific to a subject's eye (e.g., eye refractive power, intraocular pressure, and a fundus image), and an ophthalmologic control method and program.
2. Description of the Related Art
In a recent ophthalmologic apparatus, an index light flux for alignment has been projected onto a subject's eye, to generate a reference index image for alignment. The reference index image has been used to automatically drive a measurement unit in the ophthalmologic apparatus in up-and-down and right-and-left directions and in a back-and-forth direction with respect to the subject's eye. An ophthalmologic apparatus having a function of aligning a subject's eye and a measurement unit with each other by so-called automatic alignment has been the mainstream.
The ophthalmologic apparatus having such an automatic alignment function has a manual alignment function for an operator to perform a driving operation in up-and-down and right-and-left directions and in a back-and-forth direction of an optometric unit to move a measurement unit to a desired position in addition to the alignment by the automatic alignment. As to a manual alignment function, Japanese Patent No. 4428987 discusses an apparatus which shifts to a measurement mode for performing automatic alignment in a back-and-forth direction and performing manual alignment in up-and-down and right-and-left directions, when a measurement error is continued in automatic alignment.
As a case where alignment by automatic alignment cannot be performed, Japanese Patent Application Laid-Open No. 2008-295972 discusses coping with a case where a light receiving amount of noise light other than an image of a light flux for alignment reaches a threshold value for a subject's eye having a small pupil diameter. More specifically, an apparatus which detects a luminance distribution of an alignment index in a captured anterior eye image and changes a projection light amount of the alignment index or the sensitivity of a detection unit, is discussed for a subject's eye having a small pupil diameter.
However, in such an ophthalmologic apparatus which performs alignment by automatic alignment, if a subject's eye has a low cornea reflectance due to a disease, an image caused by cornea reflection of a light flux for alignment becomes dark so that alignment cannot be performed. Alternatively, if a subject's eye has a small pupil diameter, noise light other than an image of a light flux for alignment becomes bright so that alignment cannot be performed.